1. Field of the Invention
The present invention is directed to anti-dust agents for inorganic particulate materials and, more particularly, to anti-dust agents for fertilizers.
2. Description of Related Art
Inorganic particulate materials and, more particularly, fertilizers, such as disintegrating sulfur fertilizer (DSF), ammonium phosphates, calcium phosphates, ammonium nitrates, potassium nitrates, potassium chlorides, potassium sulfates, and the like are widely used. Methods of manufacturing these inorganic materials, as well as methods of processing the materials into particles via prill and granulation techniques, are also known. The inorganic particulate materials, however, often exhibit an undesirable level of dust formation. During handling or transportation, the inorganic particulate materials can break into smaller particles, resulting in unacceptable levels of dust.
Dust emission from inorganic particulate materials, such as DSF, can present ecological concerns and can be quite irritating to persons upon short-term exposure. In some cases, dust emissions from inorganic particulate materials can even form explosive mixtures with air. As used herein, dust refers to airborne particles, the majority of which are about 10 microns or smaller, created during the production and handling of fertilizers and other inorganic particulate materials.
Because of difficulties associated with manufacturing useable particulate fertilizer that does not emit unacceptable levels of dust, special anti-dust treatments often have been applied. Generally, anti-dust treatments for inorganic particulate materials, such as fertilizers, have focused primarily on petroleum-based products, mineral oils, and waxes. Each of these treatments presents disadvantages. For example, oils tend to volatilize and/or soak into the fertilizer with time and lose their effectiveness, while waxes and petroleum-based products are difficult to handle, and can require special heated application equipment. Inorganic particulate materials coated with petroleum-based products can generate residues on handling equipment, and, in the case of coated fertilizers, typically result in the separation of scum upon dissolution of the fertilizer in water.
One example of a petroleum distillate residue used as an anti-dust agent for phosphate and other fertilizers is Dustrol 3079(trademark) or Arr-Maz 3670(trademark) Petroleum-based materials of this type have a relatively high viscosity and must either be heated or diluted with a volatile solvent in order to be coated onto particles. Petroleum distillate residue material produces a sludge that can clog filters during spray application. The petroleum distillate residue material also can adversely affect the color of the fertilizer. For example, Dustrol 3079(trademark) turns DSF particles black, particularly when the residue material is recycled.
There remains a need for a more efficient and cost effective anti-dust agent for inorganic particulate materials, and especially for fertilizers such as DSF. It would be particularly desirable to develop an anti-dust agent for DSF that does not interfere with the useful disintegration of the fertilizer and that is environmentally safe.
According to one aspect of the invention, a process of reducing the formation of dust in an inorganic particulate material comprises applying to the inorganic particulate material an effective amount of an anti-dust agent. The anti-dust agent comprises at least one polyhydric alcohol represented by the formula CnH(2n+2)Om wherein 3xe2x89xa6nxe2x89xa66 and m=n or nxe2x88x921, with the proviso that mxe2x89xa73. A preferred polyhydric alcohol is glycerol. The process is particularly effective for reducing dust formation in fertilizers, including time-release fertilizers such as disintegrating sulfur fertilizer (DSF).
According to another aspect of the invention, an inorganic particulate material having reduced dust emissions comprises inorganic particles coated with an effective amount of an anti-dust agent. The anti-dust agent comprises at least one polyhydric alcohol.
The polyhydric alcohols of the present invention are efficient and cost effective agents for reducing dust formation in inorganic particulate materials, overcoming the drawbacks of previous oil- petroleum-, and wax-based anti-dust agents. The polyhydric alcohols of the present invention also are environmentally safe. Advantageously, when used with fertilizers such as DSF, the polyhydric alcohols do not interfere with useful disintegration of the fertilizer or otherwise adversely affect its useful properties and characteristics.